Vizio M51ax-J6 review: A soundbar with virtualized Dolby Atmos

Vizio’s latest mid-range soundbar is aimed at budget-conscious audiophiles who want rich Dolby Atmos and DTS:X audio without breaking the bank or requiring upfiring speakers that require flat ceilings at just the correct height.

It’s no surprise that the 5.1-channel M51ax-J6 can’t match the precision of more expensive soundbars with upfiring drivers because it uses virtualization instead of actual drivers to convey height cues. You’ll also be missing Wi-Fi connectivity and audio casting functionality, which is understandable given the M51ax-pricing J6’s and feature set.

Despite its flaws, the 5.1-channel M51ax-J6 provides a lot of value, with rich, powerful, and exciting sound, eARC support, and a dedicated audio connection for connecting a smart speaker like an Amazon Echo or Echo Dot.

Configuration of M51ax-J6

The Vizio M51ax-J6 is a nine-driver 5.1-channel soundbar by Vizio. Three oval-shaped (1.66 x 3.48-inch) full-range drivers and three 0.79-inch tweeters are included in the primary soundbar unit, which provide sound for the left, center, and right channels. A pair of passive radiators supplement those drivers, bolstering the soundbar’s bass response. The surround speakers each have one full-range (1.61 x 2.22 inch) driver, while the wireless subwoofer has a five-inch driver.


The M51ax-J6 is compatible with Dolby Atmos and DTS:X, two object-based audio technologies that provide height and surround effects (you can read about those audio formats in this other story). Rather than using up-firing drivers to bounce height cues off the ceiling, the M51ax-J6 uses virtualization—specifically, DTS Virtual:X—to fool your ears into believing they’re hearing height effects. While virtualized height channels won’t sound as precise as up-firing (or, better yet, in-ceiling) drivers, they may be preferred for individuals with vaulted, too high (above 14 feet), or too low (below 14 feet) ceilings (below 7.5 feet).

The M51ax-J6 has a pleasingly modest profile, measuring 36 x 2.2 x 3.5 inches. Indeed, the top of the unit just clears the bottom edge of my 55-inch LG C9 OLED TV, which is a welcome difference from soundbars that obstruct a sliver (or more) of the LG’s screen.

Meanwhile, at 8.25 x 8.25 x 10 inches (WxDxH), the wireless subwoofer is rather small—which is a good thing, given that most users will be placing the subwoofer near their sofas. Similarly, the surround speakers, which measure 5.6 x 3.4 x 2.25 inches (WxDxH), might be easily placed on a small shelf or (much better) installed on the wall, ideally a foot or two above your head when seated.

Inputs and outputs

The M51ax-ports J6’s and connectors are located in two rear chambers on the left and right. The right-hand side of the soundbar has two HDMI ports: an input and an output. The HDMI output not only supports ARC (Audio Return Channel), which allows TVs to send audio back to soundbars, but it also supports eARC, an improved version of ARC with enough bandwidth to deliver lossless audio formats like Dolby TrueHD and DTS-HD Master Audio.


When it comes to setup, the HDMI ports provide you a few choices. You can either connect a video source (such as a streaming player, gaming console, or Blu-ray player) to the HDMI input and then connect the HDMI output to one of your TV’s HDMI ports (4K HDR passthrough is supported) or connect the soundbar’s HDMI-ARC port to the matching HDMI-ARC connector on your TV and then connect video sources to your TV’s HDMI inputs. You’ll be able to switch between additional video sources without having to transfer cables if you choose the latter option, and you’ll be able to feed audio from your TV’s tuner and smart TV apps through the soundbar as well.

If your TV doesn’t have HDMI ports, you can use the M51ax-optical J6’s input, and if your TV doesn’t have an optical output at all, you can use the soundbar’s 3.5mm auxiliary input, which is located in the left rear chamber. (Included in the box is a stereo RCA to 3.5mm Y-cable.)

A second 3.5mm input is located just below the M51ax-3.5mm J6’s auxiliary port, and it’s used to connect a smart speaker like the Amazon Echo Dot; you can also connect a smart speaker through Bluetooth (including the Google Nest Mini, which lacks a wired output jack).


The primary M51ax-J6 soundbar device, as previously stated, may be put in front of your TV or installed on the wall behind your TV, with mounting equipment provided. Because the soundbar’s five-foot power chord terminates in a conventional two-prong connector, there’s no need to deal with a bulky, outlet-blocking AC converter.

The M51ax-tiny J6’s surround speakers link to the wireless subwoofer (which isn’t technically wireless due to its power supply) via a pair of 30-foot cords, providing you some flexibility in terms of placement.


Another option is to move the subwoofer closer to your sofa; however, if the subwoofer is too close, it will become excessively boomy.

If you don’t want to deal with surround speakers across the room from the soundbar, you have a third option: put them directly next to it, flanking the primary soundbar housing. The M51ax-J6 has two surround sound modes for this: a “Front” mode that delivers virtual surround effects while the satellite features are in the front of the room, and a “Dual” mode that sends audio from the left and right front channels to the surrounds, thus broadening the soundstage.

The M51ax-J6 comes with a wireless (well, mostly wireless) subwoofer already installed. Both units instantly connected to each other after I turned them on, with no effort on my part. If you have any connectivity issues, you can simply manually link the soundbar and subwoofer.

It’s no surprise that the M51ax-J6 lacks Wi-Fi connectivity, given its sub-$500 price tag. That means you won’t be able to use Apple AirPlay 2 or Chromecast to send audio to the soundbar, and you won’t be able to stream music directly from Spotify Connect or another streaming music provider. The lack of Wi-Fi, on the other hand, means you won’t have to worry about connecting the soundbar to your wireless network.

Controls, remote, and indicators

A power button, an input button that cycles through video and audio sources, a Bluetooth connecting button, and volume up/down controls are all located on the top of the M51ax-main J6’s chassis. The illuminated display on Vizio’s new soundbar remote gives it an advantage over its competitors, while the buttons themselves are not backlit. The remote is otherwise a jumbled mess, with a four-way navigational keypad in the middle and separate EQ, audio level, setup, and audio effect buttons beneath the navigation wheel. Fortunately, the controls you’ll use the most in the dark—volume up/down, mute—are easy to locate by touch.


Crisp, punchy, energetic, and thrilling are some of the terms I’ve used to characterise Vizio’s recent soundbars, including the more expensive M512a-H6 (which has upfiring drivers), and the M51ax-J6 gets the same praise—well, to a point.

The M51ax-J6 uses DTS Virtual:X to achieve the height effects for Dolby Atmos and DTS:X soundtracks, as I described earlier. (Dolby previously objected to third-party DSP technology being used on top of its own audio codecs, but according to Vizio, Dolby has subsequently relented.) I’ve contacted Dolby for further information.)

I began my listening testing with Star Wars: The Empire Strikes Back on UHD Blu-ray, which features a remastered Dolby Atmos soundtrack. The crisp sound of John Williams’ thrilling score and the deep roar of the Falcon’s engines struck me as I watched the Millennium Falcon perform barrel rolls with three menacing Imperial Star Destroyers in pursuit—a tad boomier than I’d like, but nothing a tweak of the subwoofer level settings couldn’t fix. (The subwoofer was also about three feet distant from my sofa.) It’s a dynamic scene, and the M51ax-J6 was an excellent match.

DTS Virtual:X won’t be able to match the sound of height cues from upfiring speakers, let alone in-ceiling speakers when it comes to height effects. The virtualization technique, on the other hand, did a decent job of presenting the hiss of frozen snow particles cascading down from the ceiling at the hidden Rebel base on Hoth, as well as the height cue of the groaning Imperial Walker foot nearly stomping on Luke. While I’ve previously grumbled about the shrillness of DTS Virtual:X in older soundbars, DTS’ virtualization this time sounded significantly more natural.

The launch scene sounded really magnificent when I switched to the UHD of Apollo 13 and its DTS:X soundtrack, from the surround cue of the gurgling fuel pumps to the roar of the Saturn V rocket as the ship ascended off the launchpad. The clear explosion of the escape tower jettison, as well as James Horner’s thrilling score, were also highlights for me. The simulated height effects lacked the precision that upfiring drivers provide, but given the M51ax-price J5’s range, my ears were satisfied.










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